The field of the invention pertains to audio reproduction loudspeakers. In particular, the invention pertains to electric crossover circuitry connected to and in combination with multiple audio transducers primarily for use in loudspeakers although not exclusively limited thereto.
The response of an electro-magnetically powered audio transducer to an electric input signal, whether complex or simple in waveform, is a complex phenomenon. Assuming the maximum time domain sound pressure amplitude response to be the desired response to an impulse input waveform, step input waveform or sinusoidal waveform, a plurality of prior and subsequent sound pressure responses of lesser amplitude will emanate from the audio transducer. Such prior and subsequent sound pressure responses are spurious and if of sufficient amplitude can significantly affect the perceived sound. "Ringing" of the audio transducer is one well known example of a subsequent spurious sound pressure amplitude response.
U.S. Pat. No. 4,130,727 to Kates discloses a means for deriving a delayed signal from the input signal to a filter and audio transducer. The delayed signal is summed with the input signal to create a modified drive signal for the audio transducer. The delayed signal is manipulated to provide input resonances complementary to the subsequent spurious sound pressure response resonances of the audio transducer thereby minimizing or cancelling the effect of the subsequent spurious sound pressure responses.
Kates discloses a plurality of active components with digital sampling techniques and mentions the possibility of using passive delay means in substitution for his active components but does not disclose a suitable passive circuit. Such a passive circuit, if realizeable for the Kates application, would likely be prohibitively expensive.
Spurious sound pressure responses prior to the desired maximum sound pressure response are essentially aperiodic in both the time and frequency domains and may be of an amplitude sufficient to be significant. The above noted means for controlling subsequent response resonances, however, do not include means for controlling non-resonant prior spurious responses such as "pre-shoot".